With everything off, I'd use a digital multimeter across battery posts, what is the reading? 10.8 volts is too low, if I understand your post? You need to also check your charging system. Use a dmm to take voltage reading, let us know. All battery cables coming and going are clean and tight on all ends? Could be excessive battery drain? You need a fully charged battery to do testing.

The autostores I deal with will come to your home, in town, give you a jump, if needed.

Rasmataz and JDL - thanks for the guidance. I did clean and tighten the battery cable connections and went through all the lights and other switches to be sure they were completely off. I was able to jump start the PT with my other car. I'm letting it charge up now. Then will check voltage again as well as see if it restarts.
Again - thank you both for your help.